Arc lamp cooling device



Sept. 8, 1953 c. s. ASHCRAFT ARC LAMP COOLING DEVICE Filed Dec. 17, 1951 nm N MW m 1 r Patented Sept. 8, 1953 UNITED STATES PATENT OFFICE ARC LAMP COOLING DEVICE Clarence S. Ashcraft, ManhassetgiN. 1'. Application December 17, 1951,-Serla1No. 262,137

7 Claims. 1

This invention relates to an improvement in a cooling device for an arc lamp.

It is common practice to provide a water jacket to cool either or both carbons of an arc lamp. The optimum condition requires the crater formed in the carbon to be as close as possible to the water cooling jacket, thereby producing greater crater brilliancy and better dissipating the heat generated in the positive carbon. However, as the carbon is used up, it is necessary to advance the position of the carbon continuously, and in the event that the operator is negligent and does not move the carbon at the proper time it may burn the jacket and thereby destroy .its usefulness. It is therefore desirable to insert some form of guard means between the crater of the carbon and the water jacket so that such protective device will be burned without substantial injury to the water jacket. This protective device should be readily removable and replaceable.

It an object of this invention to provide a protective device or guard means, which is water cooled, thereby cooling the carbon closer to the crater increasing heat dissipation, decreasing the danger of injury to the water jacket and increasing crater brilliancy.

It is a further object of this invention to provide means whereby protrusion of carbon can be maintained at a minimum distance v:from the cooling means without endangering the water jacket, thereby reducing the possibility of the carbon bein broken off and also the possibility of the operator allowing the carbon to burn back into the water jacket or other cooling device.

It is a further object of this invention to proprovide a water cooled guard for the water jacket, which can be readily removed and rep-laced without any change of the water connection.

Another problem which exists in the provision .of guard means between the crater of a carbon and the Water cooling jacket is created by the passage of current from the brushes to the carbon. Some of the current is shunted through the water jacket and through the connection between the water jacket and the guard piece to the carbon. When the carbon is carrying high currents, impurities such as copper oxide are formed in said connection, particularly when the water jacket and guard means are of difierent materials, thereby obstructing the insertion and removal of the guard means to the water jacket.

It is an object of this invention to provide means for shunting this current directly to the guard means and thereby bypassing the connection between the guard means and the water 2 jacket to insure a releasable connection between the two.

It is a further object of this invention to provide a more effective cooling device for more fully dissipating the heat in the carbon.

It is a further object of this invention to provide water cooled guard means which are of such a construction as to avoid obstructing reflected light from mirror reflector type lamps.

It is a further object of this invention to provide a guard between the crater and the water jacket which, as the device heats, up, will expand, insuring :good thermal and electrical contact.

Other objects and advantages of this invention will be apparent from the following description.

In the drawings:

Figure 1 represents a side elevation of a cooling device embodyin this invention.

Figure 2 is a sectional view taken along the line 2-4 of Figure 1.

Figure 3 is a sectional view taken along the line 3-3 of Figure 1.

Figure 4 is a sectional view taken along the line 44 of Figure 3.

Figure :5 is a perspective view of a guard piece.

:In this embodiment the device contemplates a positive carbon 1-0 which projects through centrally formed bore l 2 in water jacket [4. Although the device is equally adapted to cool the negative carbon. only the cooling of the positive carbon will be described in detail. Spaced from the water jacket M by webs I6 and I8 is a mounting plate 2a which has a suitable aperure t rough which the carbon projects. The mounting plate has suitable apertures therein to permit it to be bolted upon the remaining structure. The space between the plate 28 and the :rear extremity of the water jacket provides :a housing 3150,! the brushes generall designated :22 and 2,4. The brushes .22 and 2 each have a head portion {.25 and 2-8, respectively (see Figure 44), formed on the upper extremity thereof. The head 25 has a groove 30 out in the face thereof adapted to fit partially about the carbon 1-0,. Head .28 has a similar groove -32 for the same function. The carbon when thus gripped between the two heads 26 and :28 is in electrical contact with each of the heads substantially the full length of the grooves 30 and 32. Each of the brushes 2-2 and 26 has an arm at and 36, respectively, depending from its respective head. Each of the arms has an aperture 3? formed therein (see Figure l) and one branch as or All of the Y-shaped positive connection is at- .tached thereto by a screw 41 providin a positive charge to the carbon In through the brushes 22 and 24. The brushes 22 and 24 are retained in contact with the carbon by means of locking levers 42 and 44 (best seen in Figure 4), each of which has an inturned lip 46 adapted to overlie the rods 48 mounted between the plate 20 and. the water jacket I4. Each of the brush heads 26 and 28 of the brushes 22 and 24 is p ovided with a suitable indentation 43 and 45, respectively, provided to receive a stud 50 on the looking levers 42. The lower extremities of the locking levers 42 and 44 are provided with an inturned stud 52 (see Figure 1) and a spring 54 is mounted at each extremity on one of the studs 52 and urges the lower extremities of the locking levers 42 and 44 apart from one another. The locking levers are pivotally mounted around the rods 48 urging the upper extremities thereof towards one another, locking the brushes 22 and 24 into firm contact with the carbon I6.

Threaded into the bore I2 of the water jacket I4 is the guard generally designated 56, best seen in Figure 5, which is provided with a male threaded extremity 56 and a flange 66 at the opposite extremity, the two extremities being separated by a cylindrical body portion 62, as best seen in Figure 5. The flange 66 may have cuts 64 therein providing a finger or wrench grip to unscrew the guard 56 from the water jacket to permit its replacement. The guard 56, of course, is provided with an internal bore 66 to permit the passage of carbon In there through. It is thus apparent that the carbon II] is longitudinally movable in the water cooling device, being held in place solely by the clamping action of the brushes 22 and 24, and as the carbon is used up the operator should advance the carbon to the right, as seen in Figure 3. The protrusion of carbon through the guard 56 should be kept at a minimum so that the crater 68 formed in the carbon will be as close as possible to the water cooled guard 56 to increase the crater brilliancy.

Water is supplied to the water jacket through inlet pipe Ill, which is suitably attached to a nipple I2 at the base of the water jacket by nut I3. The water thus flows upwardly through the tube l!) into the water jacket and around the bore I2, as illustrated by the arrow in Figures 2 and 3. The Water then passes out the nipple 74 to which the guard supply tube I6 is secured by nut H. The guard supply tube is then bent upwardly and coiled about the cylindrical body 62 of the guard 56. These coils are herein illustrated as two in number and should be sufficiently small to insure metal to metal contact with the guard 56, although still permitting ready removal of the guard by unscrewing the male screw 56 from the female threads in the bore I2. It is apparent that as the carbon heats up the guard 54 will be heated and thus will expand insuring a good thermal and electrical connection between tube I6 and the guard 56. The water, after having passed through the coils about the guard 56, is discharged through tube 18.

It is, of course, readily apparent that the direction of flow of water may be reversed, that is, by entering outlet tube 18 and being discharged through supply tube Ill, without altering the operation of the device.

It is obvious that the electrical contact between the carbon and the brushes 22 and 24 insures a positive electrical connection. However, some of the current is shunted through the water jacket I4 and into the guard 56. Current through the bore I2 to the guard 56 passes through the threaded connection and normally the heat generated will cause a chemical reaction and the formation of copper oxide or other impurities in the threaded connection, thereby seriously interfering with the unscrewing of the guard 56 in the event the guard is to be replaced. The cooling device embodying this invention, however, insures a positive electrical connection between the tube I6 and guard 56 so that current flow is shunted through the tube 16, thereby bypassing the threaded connection, thus deterioration of the threaded connection is substantially eliminated.

It is, of course, apparent that in utilizing this form of guard the carbon, if permitted to burn too far by the operator, will burn the water cooled guard 56 and not the water jacket I4. It is, of course, relatively inexpensive to replace the guard 56, but it is much more expensive to have a burned water jacket necessitating replacement of the entire device. Also, the device carries the water cooling to a greater portion of the carbon and nearer the crater, more fully dissipating the heat in the carbon. It is, of course, obvious that the flange 60 may be of very small thickness to permit drawing of the crabon back closer to the water cooled body portion 62 of the guard.

The operation of this device is as follows: The carbon I0 is inserted into the bore I2 and through the aperture in the mounting plate 20. The brushes are inserted with their arms 34 and 36 inside the rods 48 and with th grooves 3|] and 32 surrounding a portion of the carbon. The locking levers 42 and 44 are positioned outside rods 48 with the lips 36 projecting around the rods 48, thereb pivotally mounting the locking levers with studs 56 inserted into indentations 43 and 45. The spring 54 is mounted between the inturned studs 52 on the lower extremities of the locking lever urging them apart, thereby securing the brushes in positive contact with the carbon. The carbon is given a positive charge through the arms 38 and 40 of the Y connection. The carbon I0 is then adjusted longitudinally in the device so that the crater 68 is adjacent the flange 60 of the guard 56 as near as is practicable. Water then enters the inlet tube I0, circulates through the water jacket I4 and is discharged into the tube 16. The water then passes through the coils about the tube 62 of the guard 56 and outwardly through the discharge tube 18, thereby cooling the guard 56 and a greater portion of the carbon I0.

It has been determined that by utilizing a water cooled guard such as 56 the arc voltage can be substantially reduced. Excessive arc voltage, of course, creates turbulence and, utilizing this invention, a greater amount of current can be used without creating such turbulence. Also, at times the arc may get out of control due to defective carbons or a voltage surge. When this occurs, the flam from the negative carbon seems to envelop the positive carbon. When the flames strike the guard or water jacket, there is an almost immediate melting. When, however, guard means as described herein are utilized, such melting is avoided.

While what hereinbefore has been described is the preferred embodiment of this invention, it is readily apparent that the details of this device can be varied without departing from the scope of this invention.

I claim:

1. In a cooling device for an arc lamp of the type having a carbon, electrical contacts to said carbon and a water jacket between said electrical contacts and the actuated extremity of said carbon, the combination with said water jacket of: a water tube to said water jacket, a guard mounted on the extremity of said water jacket opposed to said electrical contacts, and a second water tube from said water jacket, said second tube being coiled about said guard and in contact therewith.

2. In a cooling device for an arc lamp of the type having a carbon, electrical contacts to said carbon and a water jacket between said electrical contacts and the actuated extremity of said carbon, the combination with said jacket of: an internally threaded bore formed in said water jacket surrounding said carbon, a guard member having an externally threaded extremity to be screwed into said bore, a flange formed on the opposite extremity of said guard, a body portion between said flange and said threaded extremity, a water tube to said water jacket, and a second water tube from said water jacket, said second tube being coiled about the body portion of said guard and in contact therewith.

3. In a cooling device for an arc lamp of the class having a carbon, electrical contacts to said carbon, a water jacket between said electrical contacts and the actuated extremity of said carbon, a pair of water supply tubes to said water jacket, the combination with said water jacket of a guard member mounted on the extremity of said jacket opposed to said electrical contacts, and one of said Water supply tubes being coiled about said guard member.

4. In a cooling device for an arc lamp of the class having a carbon, electrical contacts to said carbon, a water jacket between said electrical contacts and the actuated extremity of said car- 6 bon, a pair of water supply tubes to said water jacket, the combination with said water jacket of: a guard member having a threaded extremity and a flanged extremity and a body portion between said extremities mounted on the extremity of said water jacket opposed to said electrical contacts, and one of said water supply tubes being coiled about the body portion of said guard member.

5. In an arc lamp of the type having positive and negative electrodes and a water jacket surrounding at least one of the electrodes adjacent its arcing, the combination with said water jacket of: guard means on the extremity of said water jacket adjacent its arcing, and means directing water from said water jacket about said guard means, thereby cooling same.

6. In an arc lamp of the type having positive and negative electrodes and a water jacket surrounding at least one of the electrodes adjacent its arcing, the combination with said water jacket of: guard means on the extremity of said water jacket adjacent its arcing, and a liquid carrying tube coiled about said guard means.

7. In an arc lamp of the type having positive and negative electrodes and a water jacket surrounding at least one of the electrodes adjacent its arcing, the combination with said water jacket of guard means on the. extremity of said water jacket adjacent its arcing, and a liquid carrying tube coiled about said guard means maintaining electrical contact with said jacket.

- CLARENCE S. ASHCRAFT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,454,957 Zimmerman Nov. 30, 1948 2,495,970 Huff Jan. 31, 1950 

